The investigator, proposes to analyze two actin binding proteins, the tropomyosin isoforms and caldesmon in regulating nonmuscle cell motility. Specifically (1) the role of nonmuscle tropomyosin isoforms in cytokinesis will be ascertained; (2) the effects of molecular manipulation of caldesmon on microfilament stability and motile behavior in mutants will be studied; (3) the role of tropomyosin isoforms and caldesmon in intracellular granule movements will be analyzed, by analyzing interaction of tropomyosin isoforms and caldesmon on interactions of actin and myosin I and actin and myosin V. Also (4) the regulation of tropomyosin isoforms will be extended to the Drosophila model in relation to transport and localization of maternal messages during embryogenesis. A combination of molecular biological, cell biological, biochemical; and immunological approaches will be used to study the role of the aforementioned proteins.